Solar radiation - what is it? total solar radiation. Solar radiation or ionizing radiation from the sun

The bright luminary burns us with hot rays and makes us think about the significance of radiation in our life, its benefits and harms. What is solar radiation? Lesson school physics invites us to start to get acquainted with the concept of electromagnetic radiation in general. This term refers to another form of matter - different from substance. This includes both visible light and the spectrum that is not perceived by the eye. That is, x-rays, gamma rays, ultraviolet and infrared.

Electromagnetic waves

In the presence of a source-emitter of radiation, its electromagnetic waves propagate in all directions at the speed of light. These waves, like any other, have certain characteristics. These include the oscillation frequency and wavelength. Any body whose temperature differs from absolute zero has the property to emit radiation.

The sun is the main and most powerful source of radiation near our planet. In turn, the Earth (its atmosphere and surface) itself emits radiation, but in a different range. Observation of the temperature conditions on the planet over long periods of time gave rise to a hypothesis about the balance of the amount of heat received from the Sun and given off into outer space.

Solar radiation: spectral composition

The vast majority (about 99%) of the solar energy in the spectrum lies in the wavelength range from 0.1 to 4 microns. The remaining 1% is longer and shorter rays, including radio waves and x-rays. About half of the radiant energy of the sun falls on the spectrum that we perceive with our eyes, approximately 44% - in infrared radiation, 9% - in ultraviolet. How do we know how solar radiation is divided? The calculation of its distribution is possible thanks to research from space satellites.

There are substances that can enter a special state and emit additional radiation of a different wave range. For example, there is a glow at low temperatures ah, not characteristic for the emission of light by this substance. This type radiation, called luminescent, does not lend itself to the usual principles of thermal radiation.

The phenomenon of luminescence occurs after the absorption of a certain amount of energy by the substance and the transition to another state (the so-called excited state), which is higher in energy than at the substance's own temperature. Luminescence appears during the reverse transition - from an excited to a familiar state. In nature, we can observe it in the form of night sky glows and aurora.

Our luminary

The energy of the sun's rays is almost the only source of heat for our planet. Its own radiation, coming from its depths to the surface, has an intensity that is about 5 thousand times less. At the same time, visible light is one of critical factors Life on the planet is only a fraction of solar radiation.

The energy of the sun's rays is converted into heat by a smaller part - in the atmosphere, a larger one - on the surface of the Earth. There it is spent on heating water and soil (upper layers), which then give off heat to the air. Being heated, the atmosphere and the earth's surface, in turn, emit infrared rays into space, while cooling.

Solar radiation: definition

The radiation that comes to the surface of our planet directly from the solar disk is commonly referred to as direct solar radiation. The sun spreads it in all directions. Taking into account the huge distance from the Earth to the Sun, direct solar radiation at any point on the earth's surface can be represented as a beam of parallel rays, the source of which is practically in infinity. The area located perpendicular to the rays of sunlight thus receives the greatest amount of it.

Radiation flux density (or irradiance) is a measure of the amount of radiation incident on a particular surface. This is the amount of radiant energy falling per unit time per unit area. This value is measured - energy illumination - in W / m 2. Our Earth, as everyone knows, revolves around the Sun in an ellipsoidal orbit. The sun is at one of the foci of this ellipse. Therefore, every year at a certain time (at the beginning of January) the Earth occupies a position closest to the Sun and at another (at the beginning of July) - farthest from it. In this case, the magnitude of the energy illumination varies in inverse proportion with respect to the square of the distance to the luminary.

Where does the solar radiation that reaches the Earth go? Its types are determined by many factors. Depending on the geographical latitude, humidity, cloudiness, part of it is dissipated in the atmosphere, part is absorbed, but most still reaches the surface of the planet. In this case, a small amount is reflected, and the main one is absorbed by the earth's surface, under the influence of which it is heated. Scattered solar radiation also partially falls on the earth's surface, is partially absorbed by it and partially reflected. The rest of it goes into outer space.

How is the distribution

Is solar radiation homogeneous? Its types after all "losses" in the atmosphere can differ in their spectral composition. After all, rays with different lengths are scattered and absorbed differently. On average, about 23% of its initial amount is absorbed by the atmosphere. Approximately 26% of the total flux is converted into diffuse radiation, 2/3 of which then falls on the Earth. In essence, this is a different type of radiation, different from the original. Scattered radiation is sent to Earth not by the disk of the Sun, but by the vault of heaven. It has a different spectral composition.

Absorbs radiation mainly ozone - the visible spectrum, and ultraviolet rays. Infrared radiation is absorbed by carbon dioxide (carbon dioxide), which, by the way, is very small in the atmosphere.

Scattering of radiation, weakening it, occurs for any wavelength of the spectrum. In the process, its particles, falling under electromagnetic influence, redistribute the energy of the incident wave in all directions. That is, the particles serve as point sources of energy.

Daylight

Due to scattering, the light coming from the sun changes color when passing through the layers of the atmosphere. Practical value scattering - in the creation of daylight. If the Earth were devoid of an atmosphere, illumination would exist only in places where direct or reflected rays of the sun hit the surface. That is, the atmosphere is the source of illumination during the day. Thanks to it, it is light both in places inaccessible to direct rays, and when the sun is hidden behind clouds. It is scattering that gives color to the air - we see the sky blue.

What else influences solar radiation? The turbidity factor should not be discounted either. After all, the weakening of radiation occurs in two ways - the atmosphere itself and water vapor, as well as various impurities. The level of dust increases in summer (as does the content of water vapor in the atmosphere).

Total radiation

It refers to the total amount of radiation falling on the earth's surface, both direct and diffuse. The total solar radiation decreases in cloudy weather.

For this reason, in summer, the total radiation is on average higher before noon than after it. And in the first half of the year - more than in the second.

What happens to the total radiation on the earth's surface? Getting there, it is mostly absorbed by the upper layer of soil or water and turns into heat, part of it is reflected. The degree of reflection depends on the nature of the earth's surface. The indicator expressing the percentage of reflected solar radiation to its total amount falling on the surface is called the surface albedo.

The concept of self-radiation of the earth's surface is understood as long-wave radiation emitted by vegetation, snow cover, upper layers of water and soil. The radiation balance of a surface is the difference between its amount absorbed and emitted.

Effective Radiation

It is proved that the counter radiation is almost always less than the terrestrial one. Because of this, the surface of the earth bears heat losses. The difference between the intrinsic radiation of the surface and the atmospheric radiation is called the effective radiation. This is actually a net loss of energy and, as a result, heat at night.

It also exists during the daytime. But during the day it is partially compensated or even blocked by absorbed radiation. Therefore, the surface of the earth is warmer during the day than at night.

On the geographical distribution of radiation

Solar radiation on Earth is unevenly distributed throughout the year. Its distribution has a zonal character, and the isolines (connecting points of equal values) of the radiation flux are by no means identical to the latitudinal circles. This discrepancy is caused by different levels of cloudiness and transparency of the atmosphere in different regions of the globe.

The total solar radiation during the year has the greatest value in subtropical deserts with a low-cloud atmosphere. It is much less in forest areas. equatorial belt. The reason for this is increased cloudiness. This indicator decreases towards both poles. But in the region of the poles it increases again - in the northern hemisphere it is less, in the region of snowy and slightly cloudy Antarctica - more. Above the surface of the oceans, on average, solar radiation is less than over the continents.

Almost everywhere on Earth, the surface has a positive radiation balance, that is, for the same time, the influx of radiation is greater than the effective radiation. The exceptions are the regions of Antarctica and Greenland with their ice plateaus.

Are we facing global warming?

But the above does not mean the annual warming of the earth's surface. The excess of absorbed radiation is compensated by heat leakage from the surface into the atmosphere, which occurs when the water phase changes (evaporation, condensation in the form of clouds).

Thus, there is no radiation equilibrium as such on the Earth's surface. But there is a thermal equilibrium - the inflow and loss of heat is balanced in different ways, including radiation.

Card balance distribution

In the same latitudes of the globe, the radiation balance is greater on the surface of the ocean than over land. This can be explained by the fact that the layer that absorbs radiation in the oceans is thicker, while at the same time, the effective radiation there is less due to the cold of the sea surface compared to land.

Significant fluctuations in the amplitude of its distribution are observed in deserts. The balance is lower there due to the high effective radiation in dry air and low cloud cover. To a lesser extent, it is lowered in areas of monsoon climate. In the warm season, the cloudiness there is increased, and the absorbed solar radiation is less than in other regions of the same latitude.

Of course, the main factor on which the average annual solar radiation depends is the latitude of a particular area. Record "portions" of ultraviolet go to countries located near the equator. This is Northeast Africa, its eastern coast, the Arabian Peninsula, the north and west of Australia, part of the islands of Indonesia, the western coast of South America.

In Europe, Turkey, the south of Spain, Sicily, Sardinia, the islands of Greece, the coast of France ( southern part), as well as part of the regions of Italy, Cyprus and Crete.

How about us?

Solar total radiation in Russia is distributed, at first glance, unexpectedly. On the territory of our country, oddly enough, it is not the Black Sea resorts that hold the palm. The largest doses solar radiation fall on the territories bordering China and Severnaya Zemlya. In general, solar radiation in Russia is not particularly intense, which is fully explained by our northern geographic location. The minimum amount of sunlight goes to the northwestern region - St. Petersburg, together with the surrounding areas.

Solar radiation in Russia is inferior to Ukraine. There, the most ultraviolet radiation goes to the Crimea and territories beyond the Danube, in second place are the Carpathians with the southern regions of Ukraine.

The total (it includes both direct and scattered) solar radiation falling on a horizontal surface is given by months in specially designed tables for different territories and is measured in MJ / m 2. For example, solar radiation in Moscow has indicators from 31-58 winter months up to 568-615 in summer.

About solar insolation

Insolation, or volume useful radiation, falling on the surface illuminated by the sun, varies significantly in different geographical points. Annual insolation is calculated for one square meter in megawatts. For example, in Moscow this value is 1.01, in Arkhangelsk - 0.85, in Astrakhan - 1.38 MW.

When determining it, it is necessary to take into account such factors as the time of year (in winter, the illumination and longitude of the day are lower), the nature of the terrain (mountains can block the sun), characteristic of the area weather- fog, frequent rains and cloudiness. The light-receiving plane can be oriented vertically, horizontally or obliquely. The amount of insolation, as well as the distribution of solar radiation in Russia, is a data grouped in a table by city and region, indicating the geographical latitude.

Solar radiation is the radiation inherent in the luminary of our planetary system. The Sun is the main star around which the Earth revolves, as well as neighboring planets. In fact, this is a huge hot gas ball, constantly emitting energy flows into the space around it. This is what they call radiation. Deadly, at the same time it is this energy - one of the main factors that make life possible on our planet. Like everything in this world, the benefits and harms of solar radiation for organic life are closely interrelated.

General view

To understand what solar radiation is, you must first understand what the Sun is. The main source of heat, which provides the conditions for organic existence on our planet, in the universal expanses is only a small star on the galactic outskirts Milky Way. But for earthlings, the Sun is the center of a mini-universe. After all, it is around this gas clot that our planet revolves. The sun gives us heat and light, that is, it supplies forms of energy without which our existence would be impossible.

In ancient times, the source of solar radiation - the Sun - was a deity, an object worthy of worship. The solar trajectory across the sky seemed to people an obvious proof of God's will. Attempts to delve into the essence of the phenomenon, to explain what this luminary is, have been made for a long time, and Copernicus made a particularly significant contribution to them, having formed the idea of ​​heliocentrism, which was strikingly different from the geocentrism generally accepted in that era. However, it is known for certain that even in ancient times, scientists more than once thought about what the Sun is, why it is so important for any life forms on our planet, why the movement of this luminary is exactly the way we see it.

The progress of technology has made it possible to better understand what the Sun is, what processes take place inside the star, on its surface. Scientists have learned what solar radiation is, how a gas object affects the planets in its zone of influence, in particular, the earth's climate. Now humanity has a sufficiently large knowledge base to say with confidence: it was possible to find out what the radiation emitted by the Sun is, how to measure this energy flow and how to formulate the features of its impact on various forms of organic life on Earth.

About terms

The most important step in mastering the essence of the concept was made in the last century. It was then that the eminent astronomer A. Eddington formulated an assumption: thermonuclear fusion occurs in the solar depths, which makes it possible to stand out a huge number energy radiated into the space around the star. Trying to estimate the amount of solar radiation, efforts were made to determine the actual parameters of the environment on the star. Thus, the core temperature, according to scientists, reaches 15 million degrees. This is sufficient to cope with the mutual repulsive influence of protons. The collision of units leads to the formation of helium nuclei.

New information attracted the attention of many prominent scientists, including A. Einstein. In an attempt to estimate the amount of solar radiation, scientists have found that helium nuclei are inferior in mass to the total value of 4 protons required to form new structure. Thus, a feature of the reactions, called the "mass defect", was revealed. But in nature, nothing can disappear without a trace! In an attempt to find "escaped" quantities, scientists compared the energy recovery and the specifics of the change in mass. It was then that it was possible to reveal that the difference is emitted by gamma quanta.

Radiated objects make their way from the core of our star to its surface through numerous gaseous atmospheric layers, which leads to the fragmentation of elements and the formation on their basis electromagnetic radiation. Among other types of solar radiation is the light perceived by the human eye. Approximate estimates suggested that the process of passage of gamma rays takes about 10 million years. Another eight minutes - and the radiated energy reaches the surface of our planet.

How and what?

Solar radiation is called the total complex of electromagnetic radiation, which is characterized by a fairly wide range. This includes the so-called solar wind, that is, the energy flow formed by electrons, light particles. At the boundary layer of the atmosphere of our planet, the same intensity of solar radiation is constantly observed. The energy of a star is discrete, its transfer is carried out through quanta, while the corpuscular nuance is so insignificant that one can consider the rays as electromagnetic waves. And their distribution, as physicists have found out, occurs evenly and in a straight line. Thus, in order to describe solar radiation, it is necessary to determine its characteristic wavelength. Based on this parameter, it is customary to distinguish several types of radiation:

• warm;
• radio wave;
• White light;
• ultraviolet;
• gamma;
• x-ray.

The ratio of infrared, visible, ultraviolet best is estimated as follows: 52%, 43%, 5%.

For a quantitative radiation assessment, it is necessary to calculate the energy flux density, that is, the amount of energy that reaches a limited area of ​​the surface in a given time period.

Studies have shown that solar radiation is mainly absorbed by the planetary atmosphere. Due to this, heating occurs to a temperature comfortable for organic life, characteristic of the Earth. The existing ozone shell allows only one hundredth to pass ultraviolet radiation. At the same time, short wavelengths that are dangerous to living beings are completely blocked. Atmospheric layers are able to scatter almost a third of the sun's rays, another 20% are absorbed. Consequently, no more than half of all energy reaches the surface of the planet. It is this "residue" in science that is called direct solar radiation.

How about in more detail?

Several aspects are known that determine how intense direct radiation will be. The most significant are the angle of incidence, depending on latitude (geographical characteristics of the terrain on the globe), a season that determines how far a particular point is from a radiation source. Much depends on the characteristics of the atmosphere - how polluted it is, how much given moment clouds. Finally, the nature of the surface on which the beam falls, namely, its ability to reflect the incoming waves, plays a role.

Total solar radiation is a value that combines scattered volumes and direct radiation. The parameter used to estimate the intensity is estimated in calories per unit area. At the same time, it is remembered that at different times of the day the values ​​inherent in radiation differ. In addition, energy cannot be distributed evenly over the surface of the planet. The closer to the pole, the higher the intensity, while the snow covers are highly reflective, which means that the air does not get the opportunity to warm up. Therefore, the farther from the equator, the lower the total indicators of solar wave radiation will be.

As scientists managed to reveal, the energy of solar radiation has a serious impact on the planetary climate, subjugates the vital activity of various organisms that exist on Earth. In our country, as well as in the territory of its nearest neighbors, as in other countries located in the northern hemisphere, in winter the predominant share belongs to scattered radiation, but in summer direct radiation dominates.

infrared waves

Of the total amount of total solar radiation, an impressive percentage belongs to the infrared spectrum, which is not perceived by the human eye. Due to such waves, the surface of the planet is heated, gradually transferring thermal energy air masses. This helps to maintain a comfortable climate, maintain conditions for the existence of organic life. If there are no serious failures, the climate remains conditionally unchanged, which means that all creatures can live in their usual conditions.

Our luminary is not the only source of infrared spectrum waves. Similar radiation is characteristic of any heated object, including an ordinary battery in a human house. It is on the principle of infrared radiation perception that numerous devices work, making it possible to see heated bodies in the dark, otherwise uncomfortable conditions for the eyes. By the way, compact devices that have become so popular recently work on a similar principle to assess through which parts of the building the greatest heat losses occur. These mechanisms are especially widespread among builders, as well as owners of private houses, as they help to identify through which areas heat is lost, organize their protection and prevent unnecessary energy consumption.

Do not underestimate the impact of infrared solar radiation on the human body just because our eyes cannot perceive such waves. In particular, radiation is actively used in medicine, since it allows to increase the concentration of leukocytes in the circulatory system, as well as to normalize blood flow by increasing the lumen of blood vessels. Devices based on the IR spectrum are used as prophylactic against skin pathologies, therapeutic in inflammatory processes in acute and chronic form. The most modern drugs help to cope with colloidal scars and trophic wounds.

It's curious

Based on the study of solar radiation factors, it was possible to create truly unique devices called thermographs. They make it possible to timely detect various diseases that are not available for detection in other ways. This is how you can find cancer or a blood clot. IR to some extent protects against ultraviolet radiation, which is dangerous for organic life, which made it possible to use waves of this spectrum to restore the health of astronauts who were in space for a long time.

The nature around us is still mysterious to this day, this also applies to radiation of various wavelengths. In particular, infrared light is still not fully explored. Scientists know that its improper use can cause harm to health. Thus, it is unacceptable to use equipment that generates such light for the treatment of purulent inflamed areas, bleeding and malignant neoplasms. The infrared spectrum is contraindicated for people suffering from impaired functioning of the heart, blood vessels, including those located in the brain.

visible light

One of the elements of total solar radiation is the light visible to the human eye. Wave beams propagate in straight lines, so there is no superposition on each other. At one time, this became the topic of a considerable number of scientific works: scientists set out to understand why there are so many shades around us. It turned out that the key parameters of light play a role:

• refraction;
• reflection;
• absorption.

As scientists have found out, objects are not capable of being sources of visible light, but can absorb radiation and reflect it. Reflection angles, wave frequency vary. Over the centuries, the ability of a person to see has been gradually improved, but certain limitations are due to the biological structure of the eye: the retina is such that it can perceive only certain rays of reflected light waves. This radiation is a small gap between ultraviolet and infrared waves.

Numerous curious and mysterious light features not only became the subject of many works, but were the basis for the birth of a new physical discipline. At the same time, non-scientific practices appeared, theories, the adherents of which believe that color can affect physical state human, psyche. Based on such assumptions, people surround themselves with objects that are most pleasing to their eyes, making everyday life more comfortable.

Ultraviolet

An equally important aspect of the total solar radiation is the ultraviolet study, formed by waves of large, medium and small lengths. They differ from each other both in physical parameters and in the peculiarities of their influence on the forms of organic life. Long ultraviolet waves, for example, are mainly scattered in the atmospheric layers, and only a small percentage reaches the earth's surface. The shorter the wavelength, the deeper such radiation can penetrate human (and not only) skin.

On the one hand, ultraviolet radiation is dangerous, but without it, the existence of diverse organic life is impossible. Such radiation is responsible for the formation of calciferol in the body, and this element is necessary for the construction of bone tissue. The UV spectrum is a powerful prevention of rickets, osteochondrosis, which is especially important in childhood. In addition, such radiation:

• normalizes metabolism;
• activates the production of essential enzymes;
• enhances regenerative processes;
• stimulates blood flow;
• dilates blood vessels;
• stimulates the immune system;
• leads to the formation of endorphins, which means that nervous overexcitation decreases.

but on the other hand

It was stated above that the total solar radiation is the amount of radiation that has reached the surface of the planet and is scattered in the atmosphere. Accordingly, the element of this volume is the ultraviolet of all lengths. It must be remembered that this factor has both positive and negative aspects of influence on organic life. Sunbathing, while often beneficial, can be a health hazard. Too long under direct sunlight, especially in conditions of increased activity of the luminary, is harmful and dangerous. Long-term effects on the body, as well as too high radiation activity, cause:

• burns, redness;
• edema;
• hyperemia;
• heat;
• nausea;
• vomiting.

Prolonged ultraviolet irradiation provokes a violation of appetite, the functioning of the central nervous system, and the immune system. Also, my head starts to hurt. The symptoms described are classic manifestations of sunstroke. The person himself cannot always realize what is happening - the condition worsens gradually. If it is noticeable that someone nearby has become ill, first aid should be provided. The scheme is as follows:

• help to move from under direct light to a cool shaded place;
• put the patient on his back so that the legs are higher than the head (this will help normalize blood flow);
• cool the neck and face with water, and put a cold compress on the forehead;
• unbutton a tie, belt, take off tight clothes;
• half an hour after the attack, give a drink of cool water (a small amount).

If the victim has lost consciousness, it is important to immediately seek help from a doctor. The ambulance team will move the person to a safe place and give an injection of glucose or vitamin C. The medicine is injected into a vein.

How to sunbathe properly?

In order not to learn from experience how unpleasant the excessive amount of solar radiation received during tanning can be, it is important to follow the rules of safe spending time in the sun. Ultraviolet light initiates the production of melanin, a hormone that helps the skin protect itself from negative impact waves. Under the influence of this substance, the skin becomes darker, and the shade turns into bronze. To this day, disputes about how useful and harmful it is for a person do not subside.

On the one hand, sunburn is an attempt by the body to protect itself from excessive exposure to radiation. This increases the likelihood of the formation of malignant neoplasms. On the other hand, tan is considered fashionable and beautiful. In order to minimize risks for yourself, it is reasonable to analyze before starting beach procedures how dangerous the amount of solar radiation received during sunbathing is, how to minimize risks for yourself. To make the experience as pleasant as possible, sunbathers should:

• to drink a lot of water;
• use skin protection products;
• sunbathe in the evening or in the morning;
• spend no more than an hour under the direct rays of the sun;
• do not drink alcohol;
• include foods rich in selenium, tocopherol, tyrosine in the menu. Don't forget about beta-carotene.

The value of solar radiation for the human body is exceptionally high, both positive and negative aspects should not be overlooked. You should be aware that in different people biochemical reactions occur with individual characteristics, therefore, for someone, even half an hour sunbathing may be dangerous. Reasonably before beach season consult a doctor, assess the type, condition of the skin. This will help prevent harm to health.

If possible, sunburn should be avoided in old age, during the period of bearing a baby. Not compatible with sunbathing cancer diseases, mental disorders, skin pathologies and insufficiency of the functioning of the heart.

Total radiation: where is the shortage?

Quite interesting to consider is the process of distribution of solar radiation. As mentioned above, only about half of all waves can reach the surface of the planet. Where do the rest disappear to? The different layers of the atmosphere and the microscopic particles from which they are formed play their role. An impressive part, as indicated, is absorbed ozone layer- these are all waves whose length is less than 0.36 microns. Additionally, ozone is able to absorb some types of waves from the spectrum visible to the human eye, that is, the interval of 0.44-1.18 microns.

The ultraviolet is absorbed to some extent by the oxygen layer. This is characteristic of radiation with a wavelength of 0.13-0.24 microns. Carbon dioxide, water vapor can absorb a small percentage of the infrared spectrum. Atmospheric aerosol absorbs some part (IR spectrum) of the total amount of solar radiation.

Waves from the short category are scattered in the atmosphere due to the presence of microscopic inhomogeneous particles, aerosol, and clouds here. Inhomogeneous elements, particles whose dimensions are inferior to the wavelength, provoke molecular scattering, and for larger ones, the phenomenon described by the indicatrix, that is, aerosol, is characteristic.

The rest of the solar radiation reaches the earth's surface. It combines direct radiation, diffused.

Total radiation: important aspects

The total value is the amount of solar radiation received by the territory, as well as absorbed in the atmosphere. If there are no clouds in the sky, the total amount of radiation depends on the latitude of the area, the altitude of the celestial body, the type of earth's surface in this area, and the level of air transparency. The more aerosol particles scattered in the atmosphere, the lower the direct radiation, but the proportion of scattered radiation increases. Normally, in the absence of cloudiness in the total radiation, diffuse is one fourth.

Our country belongs to the northern ones, therefore most years in southern regions radiation is significantly greater than in the northern ones. This is due to the position of the star in the sky. But the short time period May-July is a unique period, when even in the north the total radiation is quite impressive, since the sun is high in the sky, and the daylight hours are longer than in other months of the year. At the same time, on average, in the Asian half of the country, in the absence of clouds, the total radiation is more significant than in the west. The maximum strength of wave radiation is observed at noon, and the annual maximum occurs in June, when the sun is highest in the sky.

Total solar radiation is the amount of solar energy reaching our planet. At the same time, it must be remembered that various atmospheric factors lead to the fact that the annual arrival of total radiation is less than it could be. The most big difference between the actually observed and the maximum possible is typical for the Far Eastern regions in the summer. Monsoons provoke exceptionally dense clouds, so the total radiation is reduced by about half.

curious to know

The largest percentage of the maximum possible exposure to solar energy is actually observed (calculated for 12 months) in the south of the country. The indicator reaches 80%.

Cloudiness does not always result in the same amount of solar scatter. The shape of the clouds plays a role, the features of the solar disk at a particular moment in time. If it is open, then the cloudiness causes a decrease in direct radiation, while the scattered radiation increases sharply.

There are also days when direct radiation is approximately the same in strength as scattered radiation. The daily total value can be even greater than the radiation characteristic of a completely cloudless day.

For 12 months, special attention should be paid to astronomical phenomena as determining the overall numerical indicators. At the same time, cloudiness leads to the fact that the real radiation maximum can be observed not in June, but a month earlier or later.

Radiation in space

From the boundary of the magnetosphere of our planet and further into outer space, solar radiation becomes a factor associated with a mortal danger to humans. As early as 1964, an important popular science work on defense methods was published. Its authors were Soviet scientists Kamanin, Bubnov. It is known that for a person, the radiation dose per week should be no more than 0.3 roentgens, while for a year it should be within 15 R. For short-term exposure, the limit for a person is 600 R. Flights into space, especially in conditions of unpredictable solar activity , may be accompanied by significant exposure of astronauts, which obliges to take additional measures protection against waves of different lengths.

After the Apollo missions, during which methods of protection were tested, factors affecting human health were studied, more than one decade has passed, but to this day scientists cannot find effective, reliable methods for predicting geomagnetic storms. You can make a forecast for hours, sometimes for several days, but even for a weekly forecast, the chances of realization are no more than 5%. The solar wind is an even more unpredictable phenomenon. With a probability of one in three, astronauts, setting off on a new mission, can fall into powerful radiation fluxes. This makes even more important the issue of both research and prediction of radiation features, and the development of methods of protection against it.

shortwave radiation from the sun

Ultraviolet and X-rays come mainly from the upper layers of the chromosphere and the corona. This was established by launching rockets with instruments during solar eclipses. The very hot solar atmosphere always emits invisible short-wave radiation, but it is especially powerful during the years of maximum solar activity. At this time, ultraviolet radiation increases by about two times, and X-ray radiation by tens and hundreds of times compared with radiation in years of minimum. The intensity of shortwave radiation varies from day to day, increasing sharply when flares occur.

Ultraviolet and X-ray radiation partially ionize the layers of the earth's atmosphere, forming the ionosphere at altitudes of 200-500 km from the Earth's surface. The ionosphere plays an important role in the implementation of long-range radio communications: radio waves coming from a radio transmitter, before reaching the receiver antenna, are repeatedly reflected from the ionosphere and the Earth's surface. The state of the ionosphere varies depending on the conditions of its illumination by the Sun and on the phenomena occurring on it. Therefore, to ensure stable radio communication, it is necessary to take into account the time of day, season and the state of solar activity. After the most powerful solar flares, the number of ionized atoms in the ionosphere increases and radio waves are partially or completely absorbed by it. This leads to deterioration and even to a temporary cessation of radio communications.

Scientists pay special attention to the study of the ozone layer in the earth's atmosphere. Ozone is formed as a result of photochemical reactions (absorption of light by oxygen molecules) in the stratosphere, and its bulk is concentrated there. In total, there are approximately 3 10 9 tons of ozone in the earth's atmosphere. This is very small: the thickness of the pure ozone layer near the Earth's surface would not exceed 3 mm! But the role of the ozone layer, which extends at a height of several tens of kilometers above the Earth's surface, is exceptionally great, because it protects all living things from the effects of dangerous short-wave (and, above all, ultraviolet) radiation from the Sun. The ozone content is not constant at different latitudes and in different times of the year. It can decrease (sometimes very significantly) as a result of various processes. This can be facilitated, for example, by large quantities of ozone-depleting chlorine-containing substances emitted into the atmosphere from industrial sources or aerosols, as well as emissions accompanying volcanic eruptions. Areas of a sharp decrease in the ozone level (“ozone holes”) were found over different regions of our planet, not only over Antarctica and a number of other territories of the Southern Hemisphere of the Earth, but also over the Northern Hemisphere. In 1992, alarming reports began to appear of temporary depletion of the ozone layer over northern European Russia and a decrease in ozone over Moscow and St. Petersburg. Scientists, realizing global character problems, organize environmental research on a global scale, including primarily a global system of continuous monitoring of the state of the ozone layer. International agreements have been developed and signed to protect the ozone layer and limit the production of ozone-depleting substances.

Sun radio emission

A systematic study of the radio emission of the Sun began only after the Second World War, when it was discovered that the Sun is a powerful source of radio emission. Radio waves penetrate into interplanetary space, which are emitted by the chromosphere (centimeter waves) and the corona (decimeter and meter waves). This radio emission reaches the Earth. The radio emission of the Sun has two components - a constant, almost unchanged in intensity, and a variable (bursts, "noise storms").

The radio emission of the quiet Sun is explained by the fact that hot solar plasma always radiates radio waves along with electromagnetic vibrations other wavelengths (thermal radio emission). During large flares, the radio emission from the Sun increases by thousands and even millions of times compared to the radio emission from the quiet Sun. This radio emission, generated by fast non-stationary processes, has a non-thermal nature.

Corpuscular radiation of the Sun

A number of geophysical phenomena ( magnetic storms, i.e. short-term changes in the Earth's magnetic field, auroras, etc.) is also associated with solar activity. But these phenomena occur a day after solar flares. They are caused not by electromagnetic radiation reaching the Earth after 8.3 minutes, but by corpuscles (protons and electrons forming a rarefied plasma), which penetrate the near-Earth space with a delay (by 1-2 days), since they move at speeds of 400 - 1000 km /c.

Corpuscles are emitted by the Sun even when there are no flashes and spots on it. The solar corona is the source of a constant outflow of plasma (solar wind) that occurs in all directions. The solar wind, created by the continuously expanding corona, envelops the planets moving near the Sun and . Flares are accompanied by "gusts" of the solar wind. Experiments at interplanetary stations and artificial satellites The Earth made it possible to directly detect the solar wind in interplanetary space. During flares and during the calm outflow of the solar wind, not only corpuscles but also the magnetic field associated with the moving plasma penetrate into interplanetary space.

The Earth receives from the Sun 1.36 * 10v24 cal of heat per year. Compared to this amount of energy, the remaining amount of radiant energy reaching the Earth's surface is negligible. Thus, the radiant energy of stars is one hundred millionth of the solar energy, cosmic radiation is two billionths, the internal heat of the Earth at its surface is equal to one five thousandth of the solar heat.
Radiation of the Sun - solar radiation- is the main source of energy for almost all processes occurring in the atmosphere, hydrosphere and in the upper layers of the lithosphere.
The unit of measurement of the intensity of solar radiation is the number of calories of heat absorbed by 1 cm2 of an absolutely black surface perpendicular to the direction of the sun's rays in 1 minute (cal/cm2*min).

The flow of radiant energy from the Sun, reaching the earth's atmosphere, is very constant. Its intensity is called the solar constant (Io) and is taken on average to be 1.88 kcal/cm2 min.
The value of the solar constant fluctuates depending on the distance of the Earth from the Sun and on solar activity. Its fluctuations during the year are 3.4-3.5%.
If the sun's rays everywhere fell vertically on the earth's surface, then in the absence of an atmosphere and with a solar constant of 1.88 cal / cm2 * min, each square centimeter of it would receive 1000 kcal per year. Due to the fact that the Earth is spherical, this amount is reduced by 4 times, and 1 sq. cm receives an average of 250 kcal per year.
The amount of solar radiation received by the surface depends on the angle of incidence of the rays.
The maximum amount of radiation is received by the surface perpendicular to the direction of the sun's rays, because in this case all the energy is distributed to the area with a cross section equal to the cross section of the beam of rays - a. With oblique incidence of the same beam of rays, the energy is distributed over large area(section c) and a unit of surface receives a smaller amount of it. The smaller the angle of incidence of the rays, the lower the intensity of solar radiation.
The dependence of the intensity of solar radiation on the angle of incidence of rays is expressed by the formula:

I1 = I0 * sinh,

R \u003d Q * (1-α) - I,

The sun radiates its energy in all wavelengths, but in different ways. Approximately 44% of the radiation energy is in the visible part of the spectrum, and the maximum corresponds to the yellow-green color. About 48% of the energy lost by the Sun is carried away by infrared rays of the near and far range. Gamma rays, X-rays, ultraviolet and radio radiation account for only about 8%.

The visible part of solar radiation, when studied with the help of spectrum-analyzing instruments, turns out to be inhomogeneous - absorption lines are observed in the spectrum, first described by J. Fraunhofer in 1814. These lines arise when photons of certain wavelengths are absorbed by atoms of various chemical elements in the upper, relatively cold, layers of the Sun's atmosphere. Spectral analysis makes it possible to obtain information about the composition of the Sun, since a certain set of spectral lines characterizes a chemical element extremely accurately. So, for example, with the help of observations of the spectrum of the Sun, the discovery of helium was predicted, which was isolated on Earth later.

In the course of observations, scientists found that the Sun is a powerful source of radio emission. Radio waves penetrate into interplanetary space, which are emitted by the chromosphere (centimeter waves) and the corona (decimeter and meter waves). The radio emission of the Sun has two components - constant and variable (bursts, "noise storms"). During strong solar flares, the radio emission from the Sun increases thousands and even millions of times compared to the radio emission from the quiet Sun. This radio emission has a non-thermal nature.

X-rays come mainly from the upper layers of the chromosphere and the corona. The radiation is especially strong during the years of maximum solar activity.

The sun emits not only light, heat and all other types of electromagnetic radiation. It is also a source of a constant flow of particles - corpuscles. Neutrinos, electrons, protons, alpha particles, and heavier atomic nuclei all together make up the corpuscular radiation of the Sun. A significant part of this radiation is a more or less continuous outflow of plasma - the solar wind, which is a continuation of the outer layers of the solar atmosphere - the solar corona. Against the background of this constantly blowing plasma wind, individual regions on the Sun are sources of more directed, enhanced, so-called corpuscular flows. Most likely, they are associated with special regions of the solar corona - coronary holes, and also, possibly, with long-lived active regions on the Sun. Finally, the most powerful short-term particle fluxes, mainly electrons and protons, are associated with solar flares. As a result of the most powerful flashes, particles can acquire velocities that make up a significant fraction of the speed of light. Particles with such high energies are called solar cosmic rays.

Solar corpuscular radiation has a strong influence on the Earth, and above all on the upper layers of its atmosphere and magnetic field, causing many geophysical phenomena. The magnetosphere and the Earth's atmosphere protect us from the harmful effects of solar radiation.